(1.) Technical Field
The subject invention relates to an improved manifold assembly of the type used for distributing hot molten plastic from a central injection point or sprue to a number of mold cavities or to multiple points within one large mold cavity.
(2) Description of the Prior Art
In manifold assemblies of this type, it is necessary to maintain the hot molten plastic at a specific temperature throughout the injection material flow path. To that end, cartridge heaters which are disposed directly in the manifold flow passage or heater bands which surround the outer surface of the manifold as well as thermocouples, or the like, are employed to maintain this specific temperature as well as monitor it. The configuration or structure of the manifold also plays an important part in the efficient distribution of molten plastic. A multitude of designs exist in the prior art and range from a flat block heated manifold to cylindrical manifolds of the type disclosed in U.S. Pat. No. 4,276,014 granted June 30, 1981 in the name of Katashi Aoki and U.S Pat. No. 4,298,332 granted Nov. 3, 1981 also in the name of Katashi Aoki.
Inherent in the manufacture of flat block manifolds, however, is a multitude of manufacturing and machining processes. In addition, the industry is plagued with problems related to heat loss. More specifically, cartridge heaters, which are used to heat and control the temperature of the plastic, waste heat and are thus inefficient. Also, there exists a lack of insulating means used in conjunction with hot plastic injection molding.
The present invention overcomes all of the aforementioned problems by employing a relatively low cost, highly efficient manifold utilizing various insulating means.